A positive electrode for an alkaline secondary battery has high discharge capacity in a low temperature environment. The positive electrode included in the alkaline secondary battery has a positive electrode active material including 100 parts by mass of nickel hydroxide, and an additive including yttrium oxide. The nickel hydroxide includes an -phase single phase.

A hydride secondary battery includes: a pressure vessel; a positive electrode disposed in the pressure vessel; a negative electrode disposed in the pressure vessel; and hydrogen gas with which the pressure vessel is filled. The negative electrode contains a hydrogen-absorbing alloy. In a pressure-composition-temperature diagram, a desorption curve at 25 C. of the hydrogen-absorbing alloy has a plateau pressure of 0.15 MPa or more and 10 MPa or less. The hydrogen gas has a pressure equal to or higher than the plateau pressure at 25 C. of the hydrogen-absorbing alloy.

A positive electrode for an alkaline secondary battery includes a positive electrode substrate and a positive electrode composite material that is provided on at least one surface of the positive electrode substrate. The positive electrode substrate contains a Ni foil or a Ni-plated steel foil. The positive electrode composite material contains a positive electrode active material. The positive electrode active material contains nickel hydroxide coated with cobalt oxyhydroxide. A weight per unit area of the positive electrode composite material with respect to the one surface of the positive electrode substrate is 0.02 g/cm.sup.2 to 0.035 g/cm.sup.2.

An alkaline secondary battery negative electrode and a composition forming the negative electrode, containing an active material, a binder resin, and an electrically conductive agent containing an electrically conductive carbon material. When a value of D50 is defined to be an average particle size X and a value of D20 is defined to be a particle size Y in a cumulative particle size distribution obtained by measuring the active material using a laser diffractometry particle size distribution meter, the average particle size X is 10 m or less, and the particle size Y is in the range of 30% to 70% of the average particle size X.

The present disclosure concerns a method of producing an activated negative electrode powder for use in nickel-metal hydride (NiMH) batteries, the method comprising the steps: a) providing at least one previously cycled NiMH battery; b) isolating a negative electrode powder from the previously cycled NiMH battery; c) wet-milling or milling the negative electrode powder, thereby obtaining a mixture of the activated negative electrode powder and a byproduct rich in rare earth hydroxides; and d) separating the activated negative electrode powder from the byproduct. The disclosure further relates to an activated negative electrode powder produced by the said method, as well as battery electrodes and batteries comprising such a powder.

A high-capacity and long-life negative electrode hydrogen storage material of LaMgNi type for secondary rechargeable nickel-metal hydride battery and a method for preparing the same are provided in the present invention. A chemical formula of the negative electrode hydrogen storage material of LaMgNi type is La.sub.1-x-yRe.sub.xMg.sub.y(Ni.sub.1-a-bAl.sub.aM.sub.b).sub.z, wherein Re is at least one of Ce, Pr, Nd, Sm, Y, and M is at least one of Ti, Cr, Mo, Nb, Ga, V, Si, Zn, Sn; 0x0.10, 0.3y0.5, 0<a0.05, 0b0.02, 2.3z<3.0. The negative electrode hydrogen storage material of LaMgNi type in the present invention has excellent charge-discharge capacity and cycle life. The negative electrode hydrogen storage material of LaMgNi type can be applied in both common secondary rechargeable nickel-metal hydride battery and secondary rechargeable nickel-metal hydride battery with ultra-low self-discharge and long-term storage performance.

A method of producing electrodes includes selecting a palladium alloy, annealing the palladium alloy at a first temperature above 350 C., cold working the palladium alloy into a desired electrode shape, and annealing the palladium alloy at a second temperatures and for a time sufficient to produce a grain size between about 5 microns and about 100 microns. The method further includes etching the palladium alloy, rinsing the palladium alloy with at least one of water and heavy water, and storing the palladium alloy in an inert environment.

A negative electrode used in a nickel metal hydride secondary battery includes a negative electrode core body and a negative electrode mixture carried on the negative electrode core body. The negative electrode mixture includes hydrogen storage alloy powder which is an aggregate of hydrogen storage alloy particles, a binder, and a thickener. The hydrogen storage alloy particles have a volume mean particle size of 40 m or less and a concentration of chlorine of not less than 180 ppm to not more than 780 ppm.

A nickel hydrogen secondary battery 2 has an electrode group 22 composed of a separator 28, a positive electrode 24 and a negative electrode 26, wherein the negative electrode 26 has a negative electrode core body and a negative electrode mixture held on the negative electrode core body; the negative electrode mixture comprises a hydrogen absorbing alloy powder composed of particles of a hydrogen absorbing alloy, a powder of an electroconductive agent, and a powder of a negative electrode additive; and the electroconductive agent is a hollow carbon black whose primary particle has a hollow-shell structure, and the negative electrode additive is a fluorine-containing anionic surfactant.

An electrolytic method of loading hydrogen into a cathode includes placing the cathode and an anode in an electrochemical reaction vessel filled with a solvent, mixing a DC component and an AC component to produce an electrolytic current, and applying an electrolytic current to the cathode. The DC component includes cycling between: a first voltage applied to the cathode for a first period of time, a second voltage applied to the cathode for a second period of time, wherein the second voltage is higher than the first voltage, and wherein the second period of time is shorter than the first period of time. The AC component has a frequency between about 1 Hz and about 100 kHz. The peak sum of the voltages supplied by the DC component and AC component is higher than the dissociation voltage of the solvent.